(a) Field of the Invention
The present invention relates to an eight-speed power train of a vehicle automatic transmission that includes one simple planetary gear set, one compound planetary gear set, four clutches, and two brakes.
(b) Description of the Related Art
A variety of power trains and hydraulic control systems thereof are available. Four- and five-speed automatic transmissions are the most common. Six-, seven-, and eight-speed transmissions are being made available for superior performance and fuel mileage. The number of gear sets and frictional elements should be as low as possible, to minimize cost and weight, and maximize stability.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.